Investigation of the interactions of highly energetic particulate radiations with boron nitride nanotubes

Boron nitride nanotubes (BNNT) have been widely recognized as one of the most promising nanomaterials for cosmic radiation shielding due to their exceptional radiation-shielding effectiveness in addition to their excellent thermal and mechanical properties, while the investigations of highly energetic particles (ranging from MeV to GeV levels in the cosmic environment) irradiation on BNNT have not been conducted. In this study, the irradiations of 100 MeV protons (the most popular particles in the galactic cosmic ray) and 200 keV argon and nitrogen ions on BNNT were conducted experimentally, followed by theoretical assessments. Various analytical means were employed to characterize the BNNT structures before and after the irradiation, presenting the slightly disordered structures of BNNT after the ion beam irradiation. The numbers of atom displacements creating the BNNT structural damage were estimated based on the Stopping and Range of Ions in Matter (SRIM) program. In addition, the detailed interaction mechanism of high-energy particles with BNNT was also explored using the Particle and Heavy Ion Transport Code Systems (PHITS). The analyses show that the decrease in the crystallinity of BNNT after the irradiation primarily resulted from kinetic energy transfer from high-energy ions to B and N atoms, leading to lattice displacement and bond breakage. This investigation provides an essential insight into the BNNT feasibility under the cosmic radiation environment dominated by high-energy ions and protons.